checker: add scope validation for struct (fix #22437) (#22449)

vlib/v/ast/types.v

@@ -158,7 +158,9 @@ pub mut:
 @[minify]
 pub struct Struct {
 pub:
-	attrs []Attr
+	attrs    []Attr
+	scope    &Scope = unsafe { nil }
+	is_local bool
 pub mut:
 	embeds         []Type
 	fields         []StructField

vlib/v/checker/struct.v

@@ -441,6 +441,11 @@ fn (mut c Checker) struct_init(mut node ast.StructInit, is_field_zero_struct_ini
 	mut old_cur_struct_generic_types := []ast.Type{}
 	mut old_cur_struct_concrete_types := []ast.Type{}
 	if struct_sym.info is ast.Struct {
+		if struct_sym.info.is_local && struct_sym.info.scope != unsafe { nil }
+			&& !struct_sym.info.scope.contains(node.pos.pos) {
+			c.error('struct `${struct_sym.name}` was declared in a local scope outside current scope',
+				node.pos)
+		}
 		// check if the generic param types have been defined
 		for ct in struct_sym.info.concrete_types {
 			ct_sym := c.table.sym(ct)

vlib/v/checker/tests/struct_scope_err.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/struct_scope_err.vv:16:8: error: struct `Foobar` was declared in a local scope outside current scope
+   14 | 
+   15 | fn x() {
+   16 |     fb := Foobar{7, 8}
+      |           ~~~~~~~~~~~~
+   17 |     println(fb.bar)
+   18 | }

vlib/v/checker/tests/struct_scope_err.vv

@@ -0,0 +1,18 @@
+fn main() {
+
+	struct Foobar {
+		foo int
+		bar int
+	}
+
+	if true {
+		fb := Foobar{5, 6}
+		println(fb.foo)
+		x()
+	}
+}
+
+fn x() {
+	fb := Foobar{7, 8}
+	println(fb.bar)
+}

vlib/v/parser/struct.v

@@ -370,6 +370,8 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 			generic_types: generic_types
 			attrs:         attrs
 			is_anon:       is_anon
+			is_local:      p.inside_fn
+			scope:         p.scope
 		}
 		is_pub:   is_pub
 	}